Re: VCS comparison table

On Tue, 17 Oct 2006, Aaron Bentley wrote:

quoted

Excuse me? What does that "throws away your local commit ordering" mean?

Say this is the ordering in branch A:

a
|
b
|
c

Say this is the ordering in branch B:

a
|
b
|\
d c
|/
e

When A pulls B, it gets the same ordering as B has.  If B did not have e
and c, the pull would fail.

Sure. But that doesn't throw away any local commit ordering. The original 
order (a->b->c) is still very much there. The fact that there was a branch 
off 'b' and there is also (a->b->d) and a merge of the two at 'e' doesn't 
take away anything from the original local commit ordering. 

quoted

So generating an extra "merge" commit would be actively wrong, and adds 
"history" that is not history at all.

It's not a tree change, but it records the fact that one branch merged
the other.

But that's a totally specious "record". It has no meaning in a distributed 
SCM. There is absolutely zero semantic information in it.

The fact that you _locally_ want to remember where you were is a total 
non-issue for a true distributed system. You shouldn't force everybody 
else to see your local view - since it has no relevance to them, and 
doesn't add any information.

Maybe not in Git.

I don't think there is any in bzr either. Can you explain?

In other words, the empty merge is totally semantically empty even in the 
bazaar world. Why does it exist?

		Linus